/*
 * SHA-1 in C
 * By Steve Reid <sreid@sea-to-sky.net>
 * 100% Public Domain
 */

/*
 *      (string):sha1()
 *                  - calculate SHA1 hash
 */

#include <astra.h>
#include <utils/sha1.h>
#include <luaapi/luaapi.h>

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

#if defined(BYTE_ORDER) && BYTE_ORDER == LITTLE_ENDIAN
#   define blk0(i) (block->l[i] = (rol(block->l[i],24) & 0xFF00FF00) \
                                | (rol(block->l[i],8) & 0x00FF00FF))
#elif defined(BYTE_ORDER) && BYTE_ORDER == BIG_ENDIAN
#   define blk0(i) block->l[i]
#else
#   error "Please fix BYTE_ORDER defines"
#endif /* BYTE_ORDER */

#define blk(i) (block->l[i&15] = rol(block->l[(i+13) & 15] ^ block->l[(i+8) & 15] \
                                     ^ block->l[(i+2) & 15] ^ block->l[i&15],1))

/* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
#define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R1(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R2(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0x6ED9EBA1+rol(v,5);w=rol(w,30);
#define R3(v,w,x,y,z,i) z+=(((w|x)&y)|(w&x))+blk(i)+0x8F1BBCDC+rol(v,5);w=rol(w,30);
#define R4(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0xCA62C1D6+rol(v,5);w=rol(w,30);

/* Hash a single 512-bit block. This is the core of the algorithm. */
static void sha1_transform(uint32_t state[5], const uint8_t buffer[64])
{
    uint32_t a, b, c, d, e;
    typedef union
    {
        uint8_t c[64];
        uint32_t l[16];
    } CHAR64LONG16;
    CHAR64LONG16 *block;

#ifdef SHA1HANDSOFF
    static uint8_t workspace[64];
    block = (CHAR64LONG16*)workspace;
    memcpy(block, buffer, 64);
#else
    block = (CHAR64LONG16*)buffer;
#endif

    /* Copy context->state[] to working vars */
    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];
    e = state[4];

    /* 4 rounds of 20 operations each. Loop unrolled. */
    R0(a,b,c,d,e, 0); R0(e,a,b,c,d, 1); R0(d,e,a,b,c, 2); R0(c,d,e,a,b, 3);
    R0(b,c,d,e,a, 4); R0(a,b,c,d,e, 5); R0(e,a,b,c,d, 6); R0(d,e,a,b,c, 7);
    R0(c,d,e,a,b, 8); R0(b,c,d,e,a, 9); R0(a,b,c,d,e,10); R0(e,a,b,c,d,11);
    R0(d,e,a,b,c,12); R0(c,d,e,a,b,13); R0(b,c,d,e,a,14); R0(a,b,c,d,e,15);
    R1(e,a,b,c,d,16); R1(d,e,a,b,c,17); R1(c,d,e,a,b,18); R1(b,c,d,e,a,19);
    R2(a,b,c,d,e,20); R2(e,a,b,c,d,21); R2(d,e,a,b,c,22); R2(c,d,e,a,b,23);
    R2(b,c,d,e,a,24); R2(a,b,c,d,e,25); R2(e,a,b,c,d,26); R2(d,e,a,b,c,27);
    R2(c,d,e,a,b,28); R2(b,c,d,e,a,29); R2(a,b,c,d,e,30); R2(e,a,b,c,d,31);
    R2(d,e,a,b,c,32); R2(c,d,e,a,b,33); R2(b,c,d,e,a,34); R2(a,b,c,d,e,35);
    R2(e,a,b,c,d,36); R2(d,e,a,b,c,37); R2(c,d,e,a,b,38); R2(b,c,d,e,a,39);
    R3(a,b,c,d,e,40); R3(e,a,b,c,d,41); R3(d,e,a,b,c,42); R3(c,d,e,a,b,43);
    R3(b,c,d,e,a,44); R3(a,b,c,d,e,45); R3(e,a,b,c,d,46); R3(d,e,a,b,c,47);
    R3(c,d,e,a,b,48); R3(b,c,d,e,a,49); R3(a,b,c,d,e,50); R3(e,a,b,c,d,51);
    R3(d,e,a,b,c,52); R3(c,d,e,a,b,53); R3(b,c,d,e,a,54); R3(a,b,c,d,e,55);
    R3(e,a,b,c,d,56); R3(d,e,a,b,c,57); R3(c,d,e,a,b,58); R3(b,c,d,e,a,59);
    R4(a,b,c,d,e,60); R4(e,a,b,c,d,61); R4(d,e,a,b,c,62); R4(c,d,e,a,b,63);
    R4(b,c,d,e,a,64); R4(a,b,c,d,e,65); R4(e,a,b,c,d,66); R4(d,e,a,b,c,67);
    R4(c,d,e,a,b,68); R4(b,c,d,e,a,69); R4(a,b,c,d,e,70); R4(e,a,b,c,d,71);
    R4(d,e,a,b,c,72); R4(c,d,e,a,b,73); R4(b,c,d,e,a,74); R4(a,b,c,d,e,75);
    R4(e,a,b,c,d,76); R4(d,e,a,b,c,77); R4(c,d,e,a,b,78); R4(b,c,d,e,a,79);

    /* Add the working vars back into context.state[] */
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
    state[4] += e;

    /* Wipe variables */
    a = b = c = d = e = 0;
}

/* SHA1Init - Initialize new context */
void au_sha1_init(sha1_ctx_t *context)
{
    /* SHA1 initialization constants */
    context->state[0] = 0x67452301;
    context->state[1] = 0xEFCDAB89;
    context->state[2] = 0x98BADCFE;
    context->state[3] = 0x10325476;
    context->state[4] = 0xC3D2E1F0;
    context->count[0] = context->count[1] = 0;
}

/* Run your data through this. */
void au_sha1_update(sha1_ctx_t *context, const uint8_t* data, size_t len)
{
    size_t i, j;

    j = (context->count[0] >> 3) & 63;
    if((context->count[0] += len << 3) < (len << 3))
        context->count[1]++;
    context->count[1] += (len >> 29);
    if((j + len) > 63)
    {
        memcpy(&context->buffer[j], data, (i = 64-j));
        sha1_transform(context->state, context->buffer);
        for ( ; i + 63 < len; i += 64)
            sha1_transform(context->state, data + i);
        j = 0;
    }
    else
        i = 0;
    memcpy(&context->buffer[j], &data[i], len - i);

}

/* Add padding and return the message digest. */
void au_sha1_final(sha1_ctx_t *context, uint8_t digest[SHA1_DIGEST_SIZE])
{
    uint32_t i;
    uint8_t  finalcount[8];

    for (i = 0; i < 8; i++) {
        finalcount[i] = (unsigned char)((context->count[(i >= 4 ? 0 : 1)]
         >> ((3-(i & 3)) * 8) ) & 255);  /* Endian independent */
    }
    au_sha1_update(context, (uint8_t *)"\200", 1);
    while ((context->count[0] & 504) != 448)
        au_sha1_update(context, (uint8_t *)"\0", 1);
    au_sha1_update(context, finalcount, 8);  /* Should cause a SHA1_Transform() */
    for (i = 0; i < SHA1_DIGEST_SIZE; i++)
        digest[i] = (uint8_t)((context->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);

    /* Wipe variables */
    i = 0;
    memset(context->buffer, 0, 64);
    memset(context->state, 0, 20);
    memset(context->count, 0, 8);
    memset(finalcount, 0, 8);   /* SWR */

#ifdef SHA1HANDSOFF  /* make SHA1Transform overwrite its own static vars */
    sha1_transform(context->state, context->buffer);
#endif
}

static int method_sha1(lua_State *L)
{
    const char *data = luaL_checkstring(L, 1);
    const int data_size = luaL_len(L, 1);

    sha1_ctx_t ctx;
    memset(&ctx, 0, sizeof(sha1_ctx_t));
    au_sha1_init(&ctx);
    au_sha1_update(&ctx, (uint8_t *)data, data_size);
    uint8_t digest[SHA1_DIGEST_SIZE];
    au_sha1_final(&ctx, digest);

    lua_pushlstring(L, (char *)digest, sizeof(digest));
    return 1;
}

MODULE_LUA_BINDING(sha1)
{
    lua_getglobal(L, "string");

    lua_pushcfunction(L, method_sha1);
    lua_setfield(L, -2, "sha1");

    lua_pop(L, 1); // string

    return 0;
}
